A so-called IC card, which incorporates an IC module containing an IC chip having a microcomputer and memories therein and having a series of connection terminals for exchanging data with external devices buried in a card base, is widely known, and its standardization is in process at the ISO (International Organization for Standardization). In comparison with conventional magnetic stripe cards, since such IC cards have a larger memory capacity and are superior in security, practical usages are considered in many fields such as financial businesses, medical institutes and personal identification. The portability of the IC cards are greatly advantageous like that of conventional magnetic stripe cards. Therefore, to put the IC cards into practical use, the reliability must be securely guaranteed in the environment where the IC cards are used, that is, resistance to bending of IC card and protection of the incorporated IC chip from external stresses. Nowadays, this is an important problem.
As a conventional example, a sectional view of an IC card in Japanese Laid-open Patent Publication No. 58-92597 is shown in FIG. 8. This IC card is constructed by an IC module 32 incorporating an IC chip and having connection terminals 34 with external devices which are adhered inside of a concave 33 formed in a specified position on a card base 31 with an adhesive 35. An IC card having such a construction is produced by punching out a card base 31 in a desired size, forming a concave 33 with a size similar to an IC module 32 in a desired position, disposing the IC module 32 inside of the concave 33 of the card base 31 by using the adhesive 35 in such a way that the surface of the connection terminals 34 is flush with the surface of the card base 31.
However, in such conventional IC cards, when the both ends of the card base 31 are bent upward, the inside surface of the concave 33 strongly presses the IC module 32 inward by means of the adhesive 35, so that the IC chip incorporated in the IC module 32 might be damaged. If the IC chip is protected from the bending stress of IC card by increasing the rigidity of the IC module 32, even when the IC module 32 is pressed by the inside surface of the concave 33, because the IC module 32 is rigid, it does not change its form, and reversely, the bending stress of the card base 31 is centralized on the boundary portion between the inside surface and the inside bottom surface of the concave 33, thereby damaging the card base 31 at the boundary portion.